Supernova
Supernova A supernova is a stellar explosion that is more energetic than a nova. It is pronounced /ˌsuːpərˈnoʊvə/ with the plural supernovae /ˌsuːpərˈnoʊviː/ or'supernovas'. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval a supernova can radiate as much energy as theSun is expected to emit over its entire life span.[1] The explosion expels much or all of a star's material[2] at a velocity of up to 30,000 km/s (10% of the speed of light), driving a shock wave[3] into the surrounding interstellar medium. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant. Nova (plural novae) means "new" in Latin, referring to what appears to be a very bright new star shining in the celestial sphere; the prefix "super-" distinguishes supernovae from ordinary novae, which also involve a star increasing in brightness, though to a lesser extent and through a different mechanism. The word ''supernova''was coined by Swiss astrophysicist and astronomer Fritz Zwicky,[4][5] and was first used in print in 1926.[6] Several types of supernovae exist. Types I and II can be triggered in one of two ways, either turning off or suddenly turning on the production of energy through nuclear fusion. After the core of an aging massive star ceases generating energy from nuclear fusion, it may undergo sudden gravitational collapse into a neutron star or black hole, releasing gravitational potential energy that heats and expels the star's outer layers. Alternatively a white dwarf star may accumulate sufficient material from a stellar companion (either through accretion or via a merger) to raise its core temperature enough to ignite carbon fusion, at which point it undergoes runaway nuclear fusion, completely disrupting it. Stellar cores whose furnaces have permanently gone out collapse when their masses exceed the Chandrasekhar limit, while accreting white dwarfs ignite as they approach this limit (roughly 1.38[7] times the solar mass). White dwarfs are also subject to a different, much smaller type of thermonuclear explosion fueled by hydrogen on their surfaces called a nova. Solitary stars with a mass below approximately 9 solar masses, such as the Sun, evolve into white dwarfs without ever becoming supernovae. Although no supernova has been observed in the Milky Way since 1604, supernovae remnants indicate on average the event occurs about once every 50 years in the Milky Way.[8] They play a significant role in enriching the interstellar medium with higher mass elements.[9]Furthermore, the expanding shock waves from supernova explosions can trigger the formation of new stars.[10][11][12] Observation History Hipparchus' interest in the fixed stars may have been inspired by the observation of a supernova (according to Pliny).13 The earliest recorded supernova, SN 185, was viewed by Chinese astronomers in 185 AD. The brightest recorded supernova was the SN 1006, which was described in detail by Chinese and Islamic astronomers.14 The widely observed supernova SN 1054 produced the Crab Nebula. Supernovae SN 1572 and SN 1604, the latest to be observed with the naked eye in the Milky Way galaxy, had notable effects on the development of astronomy in Europe because they were used to argue against the Aristotelian idea that the universe beyond the Moon and planets was immutable.15 Johannes Kepler began observing SN 1604 on October 17, 1604.16 It was the second supernova to be observed in a generation (after SN 1572 seen by Tycho Brahe in Cassiopeia).13 Since the development of the telescope the field of supernova discovery has extended to other galaxies, starting with the 1885 observation of supernova S Andromedae in the Andromeda galaxy. Supernovae provide important information on cosmological distances.17 During the twentieth century successful models for each type of supernova were developed, and scientists' comprehension of the role of supernovae in the star formation process is growing. American astronomers Rudolph Minkowski and Fritz Zwicky developed the modern supernova classification scheme beginning in 1941.18 In the 1960s astronomers found that the maximum intensities of supernova explosions could be used as standard candles, hence indicators of astronomical distances.19 Some of the most distant supernovae recently observed appeared dimmer than expected. This supports the view that the expansion of the universe is accelerating.2021 Techniques were developed for reconstructing supernova explosions that have no written records of being observed. The date of the Cassiopeia A supernova event was determined from light echoes off nebulae,22 while the age of supernova remnant RX J0852.0-4622 was estimated from temperature measurements23 and the gamma ray emissions from the decay of titanium-44.24 In 2009 nitrates were discovered in Antarctic ice deposits that matched the times of past supernova events.2526 260px-Makemake hubble.png 2003 EL61.jpg 200px-Stylised Lithium Atom.svg.png Oxygen8.jpg 120px-Carbon-monoxide-3D-vdW.png 250px-Diamond-and-graphite-with-scale.jpg 220px-Insulincrystals.jpg 220px-Halite-36944.jpg 200px-VFPt dipole electric.svg.png 340px-Light-wave.svg.png 324px-Light spectrum.svg.png Category:Community Category:Category templates Category:Content Category:Template documentation Category:Site maintenance Category:Article management templates Category:Policy Category:Watercooler Category:Hidden categories Category:Browse Category:Infobox templates Category:General wiki templates Category:Organization Category:Site administration